Technical Field
The disclosure is related to an image compression method, and particularly to an image compression method based on JPEG-LS.
Related Art
JPEG-LS is an image compression standard which is lossless or approximately lossless. The standard is built for providing a more effective image compression compared with JPEG.
In practice, JPEG-LS is divided into modeling and encoding. In modeling, JPEG-LS is capable of achieving excellent decorrelation effect. The core technique of JPEG-LS is low complexity lossless compression for images (LOCO-I) algorithm. The LOCO-I algorithm utilizes the prediction for the residuals, modeling, and context-based coding. The algorithm has lower complexity than JPEG algorithm because the algorithm takes the residuals as the two-sided geometric distribution, which is also called discrete Laplace distribution, and the Golomb-like codes.
However, in the procedure of modeling, the compression value of each pixel has dependency over other pixels. Therefore, the compression procedure has to be performed pixel by pixel and the timing latency is inevitable. On the other hand, the sequence of the decompression procedure is necessarily the same as the sequence of the compression procedure, so the problem of timing latency and the inefficiency in hardware exists.